In the mouth, there is a natural equilibrium between hydroxyapatite being dissolved from the enamel of teeth, on the one hand, and hydroxyapatite being formed on or in the teeth from substances occurring naturally in the saliva, on the other. This equilibrium is shifting continuously. Among other factors, it is determined by diet and physical condition. If the equilibrium is such that hydroxyapatite is dissolved, a cariogenic condition arises which is referred to as demineralization. If the equilibrium is such that hydroxyapatite is being formed in demineralized enamel, this is referred to as remineralization. By remineralization, pre-existing tooth decay and caries can be reduced or eliminated by natural means.
It has long been known that fluoride-providing compounds, even in low concentrations, promote the remineralization process and thereby reduce pre-existing carious conditions in the tooth structure.
Xylitol has been disclosed in patent and literature publications for the treatment of dental structures to provide sweetened non-cariogenic compositions, control dental plaque, prophylactic prevention of occurrence of carious conditions, and/or remineralization of pre-existing carious conditions. Barth U.S. Pat. No. 3,932,604 and its divisional U.S. Pat. No. 3,970,747, are directed to dentifrices containing substantial amounts of xylitol as a non-cariogenic sweetener/humectant, and discloses formulations also containing sodium monofluorophosphate; no remineralizing effect is disclosed. Hoffman-LaRoche Irish Patent Application 307/76, filed Feb. 16, 1976 and opened to public inspection Sept. 1, 1976 (based on Swiss Application 2158/75), discloses oral compositions containing xylitol, but no fluoride, for remineralizing dental caries. EP Publication No. 0138705, published in Patent Bulletin 85/17, discloses anti-caries compositions containing xylitol and mixtures of at least two fluoride salts providing at least 2,000 up to 20,000 ppm total fluoride ion. EP Publication No. 0251146, published Jan. 7, 1988 in Patent Bulletin 88/01, discloses oral compositions having a dental plaque preventing, and thus caries-prophylactic, activity containing a synergistic mixture of at least one fluorine compound, at least one zinc ion releasing compound (astringent), and xylitol.
It is an object of this invention to provide a new and improved method of remineralizing demineralized portions of tooth structures. Another object of the invention is to provide such a process yielding unexpectedly improved remineralization effects. Other objects and advantages will appear as the description proceeds.